A dot impact printer is known in which an impact is applied to an ink ribbon with a dot point, i.e., a small mechanical impacting element, and ink from the ink ribbon is transferred to a printing medium. Generally, an ink ribbon used in the dot impact printer is a continuous loop. For this reason, a user may continuously use the ink ribbon without exchanging the ink ribbon even when the ink ribbon has made a complete loop in use.
If an ink ribbon continues to be used after it has travelled over an entire loop, the printing quality of the dot impact printer using that ink ribbon deteriorates. A user is thus required to exchange the ink ribbon at an appropriate timing, before a full loop of the ink ribbon has traveled past the printing point, in order to maintain printing quality in a predetermined or higher level.